#include "apue.h"

static void sig_quit(int);

int main(void) {
	sigset_t newmask, oldmask, pendmask;
	if (signal(SIGQUIT, sig_quit) == SIG_ERR)
		err_sys("can not catch SIGQUIT");

	sigemptyset(&newmask);
	sigaddset(&newmask, SIGQUIT);
	if (sigprocmask(SIG_BLOCK, &newmask, &oldmask) < 0)
		err_sys("SIG_BLOCK error");
	sleep(5);
	if (sigpending(&pendmask) < 0)
		err_sys("sigpending error");
	if (sigismember(&pendmask, SIGQUIT))
		printf("SIGQUIT pending\n");
	
	if (sigprocmask(SIG_UNBLOCK, &newmask, NULL) < 0)
		err_sys("SIG_SETMASK error");
	printf("SIGQUIT unblocked\n");

	sleep(5);
	exit(0);
}

static void sig_quit(int signo) {
	printf("caught SIGQUIT\n");
	if (signal(SIGQUIT, SIG_DFL) == SIG_ERR)
		err_sys("can not catch SIG_DFL");
}
